Sometimes people do have spotting before their periods, but it is not an indication of pregnancy if all of your ultrasounds point to conception no earlier than early January.
okay thank you so very much! so in other words I did not conceive December 12 or at least it is very very unlikely? I'm confused as to why I spotted before my period on Dec 24 because I'm always very regular.
Usually if you had an ultrasound really early (and 5-6 weeks is definitely that) you would use that ultrasound for dating conception. The one on February 20 where you were in your seventh week would also do, for trying to estimate when conception might have been. Later ultrasounds have a bigger margin for error when used to try to date the pregnancy, but not early ones.
For a due date of October 6, your most likely conception date would have been January 13. Even if you got your due date of September 30 in a much later ultrasound, the likely conception date from that would be January 7. Neither of those has anything to do with December 12.
my first visit due date was Oct 6 but now it's sept 29. I'm 30 weeks today
With all of those ultrasounds, what estimated due date has the doctor given you? And is it the same one each time?